The subject matter disclosed herein relates generally to combustion machines and, more specifically, to systems and methods for use in evaluating the operation of a combustion machine having a flame sensor.
At least some known combustion machines, such as combustion engines, include one or more flame sensors that detect ultraviolet (UV) radiation. In such machines, relatively high UV radiation indicates the presence of a flame, whereas relatively low UV radiation indicates the absence of a flame. When the flame sensor indicates the absence of a flame (a “flame-out” condition), a combustion machine controller may abruptly disable the combustion machine, such as by terminating fuel delivery, to prevent a hazardous build-up of combustible fuel.
The operation of a flame sensor may deteriorate over time due to, for example, the accumulation of dirt and/or combustion byproducts on the sensor (e.g., on the sensor lens). More specifically, the accumulation of such materials may cause the flame sensor to under-detect UV radiation. Further, such materials, when positioned between the flame sensor and a flame, may absorb a portion of the UV radiation produced by the flame and thus reduce the amount of UV radiation detected by the sensor. Accordingly, the flame sensor may indicate the absence of a flame when a flame is present. Such an errant indication may be referred to as a false negative result or a “fake flame-out” condition. The controller may be unable to distinguish a fake flame-out condition from a true flame-out condition. Accordingly, the controller may abruptly disable the combustion machine, decreasing output and/or exposing the combustion machine to unnecessary wear.